Threshold assemblies are typically associated with door and window assemblies, and provide a transition from an exterior or outside environment to an interior space of a building. Such threshold assemblies are anchored to or comprise the lower, horizontal jamb of a door or window frame, and are intended to provide sealing and a weather-proofing barrier for the door or window assembly. For instance, threshold assemblies should provide adequate run-off for rain or condensation so that there is no accumulation of water in or around the door or window frame that may cause mildew, rot or other water damage. Over an extended period of time, even small amounts of water can eventually lead to water damage or fungal growth in the surrounding building walls.
Weather-stripping alone may not be completely effective to prevent water accumulation in or around the door or window frame or subsequent water leakage into the interior of the building in normal situations; and particularly in those situations where the door or window assembly is subjected to high driving winds and pressure differentials on opposite sides of the door or window. High winds and pressure differentials have a tendency to drive water or air into and past weather-stripping. For instance, it has been found that weather-stripping solely at the front of a door or window assembly fails to provide an effective barrier to entry of water and air into the associated threshold assembly and thus, water and air may leak past such a weather-stripping configuration under various conditions.
Building standards in many countries of the world are becoming more stringent in prohibiting the intrusion of wind blow rain water or condensation, for example, into the interior of buildings through door or window assemblies. To this end, various types of drainage systems have been designed and incorporated into threshold assemblies in attempt to channel water away from the thresholds and thus, reduce or eliminate the accumulation of water in the thresholds or subsequent water leakage into the interior of buildings. Despite these efforts, window and door drainage systems persist as being a common source for the infiltration of wind-blown or pressure differential driven water through door and window assemblies.
Recently, the American with Disabilities Act (ADA) has promulgated a set guidelines for buildings and facilities. The guidelines provide, among other things, specified dimensions or dimension ranges to which building structures should follow for proper handicap accessibility. As one example, the guidelines state that threshold assemblies, provided at a doorway, should not exceed ¾-inch in height for exterior sliding doors or ½-inch for other types of doors. The guidelines go on to recite that changes in level up to ¼-inch can be vertical and do not need an edge treatment; however, changes in level between ¼-inch and ½-inch should have a beveled slope equaling 1:2, and changes in level greater than ½-inch should be equipped with a ramp. Many existing door drainage systems, which attempt to channel water away from the threshold assemblies, fail to meet the ADA threshold size guidelines, thereby minimizing their utility and desirability.
What is needed is a window or door assembly drainage system that permits the ready evacuation of rain water or condensation, while preventing heavy winds or pressure differentials from forcing rain or condensation into a door or window threshold assembly and subsequently into an interior of a building. What is further needed is threshold which may be designed to meet both the ADA guidelines and any applicable building water intrusion standards.